1. Field of the Invention
The present general inventive concept relates to a projection-type 3-dimensional (3-D) image display device, and more particularly, to a projection-type 3-D image display device achieving a small size thereof by realizing a 3-D image using a single projector and improving a resolution of the 3-D image.
2. Description of the Related Art
Generally, a 3-D image is realized using the principle of stereo visual sense through two eyes of a human being. A binocular parallax, which occurs because left and right eyes of a viewer are located about 65 mm apart from each other, is the most important factor producing a cubic effect. A 3-D image display may be a display using glasses or a glassless display. The glassless display obtains a 3-D image by separating left/right images without using glasses. The glassless displays may be classified into a parallax barrier type display and a lenticular type display.
The parallax barrier type display alternately prints images that should be seen respectively by the left and right eyes in the form of a vertical pattern or a photo (in order to see the printed image using an extremely thin vertical lattice column, i.e., a barrier). By doing so, a vertical pattern image that is to be provided to the left eye and a vertical pattern image that is to be provided to the right eye are distributed by the barrier, and images at different viewpoints are seen by the left and the right eyes, respectively, so that a stereo image is perceived.
A projection-type image display device enlarges an image formed by a display element, projects the enlarged image on a screen unit using a projection lens unit, and realizes a 3-D image using a left/right eye image separation unit included in the screen unit. FIG. 1A is a schematic view of a conventional projection-type image display device. The conventional projection-type image display device includes a first projector 10 and a second projector 20, and produces a 3-D image by separating images into first images from the first projector 10 and second images from the second projector 20 and sending the first and second images to a right eye (RE) and a left eye (LE), respectively, using a screen unit S.
The screen unit S has a parallax barrier 25 in order to separate the images from the projectors 10 and 20 into the first images for the RE and the second images for the LE. Referring to FIG. 1A, the parallax barrier 25 has slits 26 and barriers 27 arranged in an alternate manner. The images from the first and second projectors 10 and 20 are separated into the first images L for the LE and the second images R for the RE by the slits 26 to form the 3-D image.
According to a conventional method, since the images are formed and blocked by the slits 26 and the barriers 27, respectively, the images L are formed, e.g., at even-numbered lines only and blocked by the barrier 27 so that black lines K are formed at odd-numbered lines as illustrated in FIG. 1B. Similarly, the images R are formed, e.g., at odd-numbered lines only and blocked by the barrier 27 so that the black lines K are formed at even-numbered lines.
Therefore, the resolution of the conventional projection-type image display device as well as the brightness of the 3-D image, deteriorates. Further, since the two projectors 10 and 20 are used to produce the images L and R, a volume of the conventional projection-type image display device is increased, not meeting a consumer's demand for a small size device.